Method for drying of the interior of a traveling flexible sleeve



Jan. 16, 1968 0. A. BRAFFORD 3,36

METHOD FOR DRYING OF THE INTERIOR OF A TRAVELING FLEXIBLE SLEEVE FiledApril 9, 1965 INVENTOR. flan 4Z0 A gwfi'aw 1g g E E 5 Z ATTORNEYS UnitedStates Patent 3,363,323 METHOD FOR DRYING OF THE INTERIOR OF A TRAVELINGFLEXIBLE SLEEVE Donald A. Bralford, Beloit, Wis., assignor to BeloitCorporation, Beloit, Wis., a corporation of Wisconsin Filed Apr. 9,1955, Ser. No. 446,852 1 Claim. (Cl. 34-6) The instant invention relatesto a drying method and more particularly to a method for the drying ofthe interior of a traveling flexible sleeve, preferably a flexiblesleeve of plastic material.

It is known that plastic materials are cast from their molten formthrough a generally circular orifice with a certain predeterminednominal amount of gas pressure in the interior thereof continuously anddirectly into a liquid which effects the solidification of the plasticmaterial into its sleeve form. Generally, the patent literature showsthis arrangement with the orifice for feeding the molten body of annularplastic material directly into such liquid with a pair of nip-definingrolls submerged in the liquid so that there will be continuouslymaintained a liquid level along the outer periphery of such plasticsleeve and also the nip-defining rolls will maintain a column ofcomparable if not the exact height of liquid in the interior of suchsleeve or primarily annular plastic material which is collapsed at suchnip. This column of liquid is ordinarily water and so is the liquidwhich is in contact with the outer periphery of the sleeve. Water orwhatever cooling material is used, however, will generally be used tocontact both the inner periphery and outer periphery of the plasticmaterial as it is converted from molten to solid sleeve and subsequentlywhen it is collapsed by the nipdefining rolls. The nip-defining rollstend to hold the column of liquid in the interior thereof at apredetermined level and this overall arrangement is shown in any numberof prior art patents.

It So happens that particularly in the case of plastic materials theamount of pressure which can be applied at the submerged nip rolls islimited by that which the plastic itself can stand, even though an idealarrangement would call for 'sufiicient pressure to preclude any of theliquid from passing through the nip in the interior of the collapsedsleeve. Instead, however, a certain amount of liquid does pass throughthis nip in the interior of the collapsed sleeve andthis liquid material(usually water) is not desirable and subtracts from the marketability ofthe plastic, whether or not the plastic is ultimately slit or otherwisetreated during whatever conventional or nonconventional conversionprocedures the plastic sleeve might be subjected to.

Generally some procedure, method or apparatus must be used to try to dryand/ or remove the liquid that was originally in the column maintainedwithin the sleeve at the time of conversion from molten to solidmaterials and, as those skilled in the art will appreciate, this type ofremoval of liquid is not particularly easy because it is ratherdiflicult to reach the interior of such sleeve with any sort of device.

The instant invention, however, provides a unique method of disposing ofthe so-called liquid impurities or drying the liquid by removal thereoffrom the inner periphery of this sleeve subsequent to initial collapsingof the same by the submerged nip rolls in the bath in which the plasticsleeve undergoes conversion from molten to solid plastic. Again, theprior art has shown anynumber for accomplishing this particularprocedure and many of these devices include slitting of the plasticsleeve at some area remote from the aforesaid bath in which the annularmolten plastic is converted to a solid plastic sleeve; but

all of these devices appear to leave something to be desired by way ofcommercial practicability or otherwise.

In the instant invention, however, there has been provided a uniquemethod for effecting removal of the very small amount of liquid whichpasses through the initial submerged nip in the so-called phase changebath, which is an adequate term to define the bath which contacts boththe inner periphery and exterior periphery of the molten plasticmaterial for purposes of converting the same from its initial molten orliquid condition to its comparatively solid (even though flexible)condition at the time that it is collapsed .by the initial submerged nipbetween rotary members or rollers in such bath. The instant invention isnot concerned with the specific details of this arrangement.

Moreover, the instant invention is not concerned with devices which maybe used to remove the liquid bath from the outer peripheral surface ofsuch sleeve either in its expanded or its collapsed condition after itis removed from the so-called phase change bath previously described.Instead, the instant invention is concerned with the more fundamentaland much more difficult concept of removing the minute amounts of liquidwhich escape from the column contacting the inner periphery of theliquid in such phase change bath through the submerged initialcollapsing nip.

Typical examples of prior art disclosures which show the phase changebath and the overall assembly which has just been described include thefollowing patents:

Voss, 1,942,990, Jan. 9, 1934; Weingand, Re. 19,329, Sept. 25, 1934;Wiley, 2,409,521, Oct. 15, 1946; Grotenhuis, 2,450,457, Oct. 5, 1948;Stephenson, 2,452,080, Oct. 26, 1948; Francis, 2,476,140, July 12, 1949;and Irons, 2,541,064, Feb. 13, 1951.

Also, various wiping and/or drying means are knownto be used to removethe phase change bath liquid from the outer peripheral surface of theplastic sleeve either in collapsed or expanded condition thereof.

With respect to the interior peripheral surface of such sleeve, however,it must be appreciated that only traces of the liquid from the column ofliquid of the phase change bath ordinarily maintained by the submergedroll nip are able to pass through this nip and be retained on the innerperiphery of the plastic sleeve, whether'or not it is collapsed. Theinstant invention relates to methods and apparatus for effecting theremoval of these traces which subtract from the marketability of thesolid flexible plastic material, whether in closed sleeve condition orin slit opened single sheet condition. It will be appreciated thatsimply slitting the sleeve to obtain a single sheet may possibly afiorda means of reaching the previously defined inner periphery of the sleeveand removing these traces of liquid, but in many instances this does nothappen to be the desirable procedure, or, alternatively, it ispreferable to remove these traces of liquid from the inner periphery ofthe sleeve before slitting and/or other conversion procedures. Theconversion procedures also are not considered to be an essential part ofthe instant invention, although it is certainly expected that at leastconventional conversion will occur ultimately in the treatment of thesleeve. Such conversion may merely involve the creation of superimposedcollapsed sleeve sections in the stack or the creation of a roll ofcollapsed sleeve for transportation or other subsequent more detailedconversion; or the conversion may actually involve the slitting of thesleeve and reslitting of the same repeatedly to obtain a plurality ofsingle sheet widths of the desired width which again may be formed intosuperimposed generally planar stacks, rolls, etc.

Instead, the instant invention affords a novel and unique method that ispositioned between the previously 3 discussed submerged initialnip-defining rolls in the phase change bath and the various conversiondevices which may be used in any number of conversion processes.

In substance, the instant invention involves an arrangement wherebyparticulate material of slight but still effective weight isincorporated within the sleeve and is permitted to engage the innerperiphery thereof such that the collapsed sleeve is again re-expanded toat least a certain extent and this particulate material serves tocontinuously pick up the traces of liquid passing by on the innerperiphery of the sleeve so that the inner peripheral surface of thesleeve is rendered free from such liquid prior to the so-calledconventional conversion station, no matter what procedure may becontemplated for conversion. It will be appreciated that one cannot usemerely any type of liquid capturing device to engage the inner peripheryof the sleeve at this stage in the production of a closed plasticsleeve, because of a number of practical reasons which include inabilityof certain materials to actually contact all areas of the innerperiphery of the sleeve, inability of certain materials to remove suchtraces of liquid for any practical length of time during operation,inability of such devices to actually carry away the traces of liquidremoved from the inner peripheral surface because of lack of escapearrangements, etc. Accordingly, the instant invention is unique in thatit affords an answer to these various practical problems. In fact, oneof the initial more practical problems is the changing of the flattenedor collapsed tube which has the form of a pair of sheets with the innerperipheral surface forming the contiguous faces thereof in actualcontact with each other; and the problem of merely separating theseso-called contiguous faces of the sheets of the previously identifiedinner periphery of the plastic sleeve is not simple when one considersthat it may be desirable, and in the case of the present invention it isnot only desirable but possible, to effect this removal of traces ofliquid without actually slitting the sleeve and opening the same to forma single sheet which may then be wiped free of such traces or mayotherwise be treated for removal of such traces of liquid carriedthereon.

It is thus an important object of the instant invention to remove tracesof liquid from the inner periphery of a traveling closed sleeve ofmaterial without slitting the same continuously and by the use ofappropriate means which are not otherwise harmful to the sleeve itselfor to the inner periphery thereof. It should also be mentioned that theliquid which forms the traces on the inner periphery of the sleeve isusually so difiicult to volatilize and the plastic sleeve itself isusualy thermoplastic in nature such that it is rendered molten withouttoo much difliculty, such that simply heating of the sleeve will nothelp in this situation. Moreover, the heating of the sleeve wouldpossibly serve to volatilize these traces of liquid but escape of suchvaporized traces of liquid still remains as a practical problem, whichwould not be solved by mere heating and which is solved in the practiceof the instant invention.

It is, therefore, an important object of the instant invention toprovide a method for removing traces of liquid for a traveling sleeve atthe inner periphery thereof without disturbance of the sleeve structure,including slitting of the sleeve.

Other and further objects will become apparent to those skilled in theart from the following detailed disclosure thereof and the drawing whichis here shown in generally schematic fashion.

Referring to the drawing, it will be seen that the collapsed sleeve isindicated as initially approaching the device at and then passingthrough a series of serpentine convolutions 10a, 10b, 10c, 10d, etc.which serpentine convolutions are defined by or effected by passing thecollapsed sleeve 10 over first an upper roll 11a and then a lower roll11b, then an upper roll 110, then a lower roll 11d, and so on aboutrolls v11e through 11k 7 tension reduction in the tube portion 10g suchthat the J in a system sometimes referred over-all as afestoon-construction for tension. It will be appreciated that the upperrolls 11a, 110, 11a, 11g and 11h are equipped for movement toward andaway from the lower rolls 11b, 11d, 11 11g, etc. and in this way theoverall tension onthe collapsed sleeve 10 is maintained relativelyconstant as it passes through such festoon which is indicated generallyby the reference numeral 11, the collapsed sleeve 10 is maintained atthe desired, usually constant tension from roll to roll on each of therolls 11a, 11b, etc. The tension maintenance devices are indicatedherein by double headed arrows marked d in each case and need not bedescribed in further detail herein for the reason that these devices areall well understood by skilled workers in this and many other arts. Thelower rolls 11b, 11d, etc. could also, of course, be equipped with meansfor moving the same so that they too'could cooperate in or actuallyeffect the desired tension control but this is ordinarily not practicaland, in fact, the lower rolls 111) through 11g are often maintained in abath B of additional cooling liquid which is shown here schematically inorder to further reduce the temperature of the collapsed sleeve 10. Itwill be appreciated that the sleeve 10 is not collapsed until the innerperiphery has substantially lost its tendency to effect sticking ofcontiguous collapsed faces thereof, but additional cooling may often bedesirable for any number of reasons which those skilled in the art willappreciate. The problem is that the inner periphery of this collapsedplastic tube still maintains traces of liquid that were carried throughthe initial submerged nip (not shown) from the initial column of phasechange liquid in the first bath into which the molten annular plasticbody (again not shown) was originally fed in the formation of theplastic tube 10.

It will also be appreciated that if there is a break in the collapsedplastic tube, for example, beyond the festoon in the region 10d even inthe earlier portions of the festoon 11, the devices a originallyintended to maintain the, desired, presumably constant, tension may thenbe used to quickly take up slack and otherwise generally maintain thecollapsed tube 10 in a desired condition for patching or whatevermaintenance might be required in order to put the collapsed tube 10 backtogether in one form or another and reestablish its progress through thefestoon 11. Y

It will also be noted that the collapsed tube passes around a lower roll11k in a region designated 10a and then through first and secondnip-defining rolls 12 and 13, respectively and subsequently throughthird and fourth'nip-defining rolls 14 and 15 respectively, from whichthe collapsed tube, then designated 10 continues onto theconversionsystem (not shown). In the region between the nip N1 definedby the two rolls 12 and 13 and the second nip N-2 defined by the tworolls. 14 and 15, it will be seen that the previously collapsed plastictube undergoes an expansion and is designated 10g. It will beappreciated that this expansion does not necessarily make the tubecompletely annular in configuration or cross section, but it does expandthe same between the two nips N-1 and N-2. Also, in order to guide theexpanded tube 10g into the second nip N-2 it will be seen that sideboards or guides 16 and 17 that are generally commensurate with thecollapsed width of the tube 10 serve to aim the tube 10 toward'thesecond nip N-2. These guides 16 and 17 may or may not actually contactthe outer'periphery of the tube 10, but usually they do or they areprovided with some sort of a blanket of gas or similar non-deleteriousfluid which might serve to avoid direct contact between the solid sideboards 16 and 17 but would materially assist in the guiding functionwhich is intended for these side boards 16 and 17.

It will also be noted that the nip N+2 is positioned substantially abovethe nip N-l and these nips are spaced apart in such a manner as topermit a certain amount of tube is permitted to change from itsoriginally collapsed condition previously described to a condition inwhich it is opened at least to some extent. The tube itself is formed ofa solid elastomer in the preferred embodiment of the invention, so it isnot necessary actually to have the positioning of the nips N-l and N-Zin such a relation of spacing that a collapsed tube would not passtherebetween at substantially the same tension as is used in the festoon11, although this certainly is helpful. Also, the tube in both collapsedand expanded forms, e.g. at a and 10g, is made of flexible material andit is thus capable of going through the various convolutions and/ ordirection changes herein described without any harm thereto. In fact,the flexibility is such that there is no harm to the tube and itsmodulus of elasticity and/or tendency to rupture is not exceeded by anyexpansion which may take place within the region 10g in the preferredoperation of the invention which will be described in further detailhereinafter.

It will further be understood that the festoon rolls of the sequence11a, etc. and the nip-defining rolls 12 through are ordinarily driven asa group or at least partially so as to maintain the desired linear speedof the tube 11 in both collapsed and open form through the overallassembly, although such drive means are also well understood by theskilled workers in the art and need not be described in any detailherein. In the drawing, the drive means are indicated in the series Rthrough R generally schematically, in view of the fact that the skilledworker will readily recognize the nature and character thereof and willnot need any disclosure of further details to comprehend the same. Moreor less drive means may be used with the various rolls described hereinto carry out the intended function, which is merely that of driving thetube 10 at a generally constant linear speed while maintaining thedesired tension, which is generally constant in the festoon and which issomewhat increased usually between the nips N-l and N-2.

Referring now to the means for removing the traces of liquid that may becarried on the interior periphery of the tube 10, it will be seen thatwithin the opened tube portion 10g there is shown a myriad of fineparticles which actually form a bed of particles 20 defined by theinterior of the expanding tube 10g leaving the oflf-running side of thenip N-l. These particles will, of course, have at least suflicientlygreat weight to overcome whatever pressures there might be in theambient atmosphere and/or in any atmosphere, air jets, or other fluidmeans which might be driven against the outer periphery of the plasticsleeve 10 in the region 10g, so that the particle bed 20 will in factassist in if not entirely effect the expansion of the collapsed tube tothe form shown in the drawing. The particles in the bed 20 are, ofcourse, shown in exaggerated size. These particles need not behomogeneous in character and, in fact, if air jets and the like are tobe used to remove traces of, for example, moisture from the outerperiphery of the sleeve in the region of 10g (by virtue of the bath Bwetting the same), then it might be desirable to include a certainamount of shot or other relatively heavy metal spheres as a part of theoverall bed 20. In any event, the bulk of the bed 20 is such that itdoes serve to open the collapsed tube in the region 10g at theoff-running side of the first nip N1. In addition, the nature andcharacter of the particles in the bed 20 is such that they do not simplystick to a wetted portion of the inner periphery of the tube and riseupwardly to plug or otherwise interfere with a nip function at thesecond nip N2 between the rolls 14 and 15. Of course, the two nips N-tland N-Z need not be superimposed and all that is required of the secondnip N2 and the rollers 14 and 15 is that they do not pass particles fromthe bed 20 and they do not permit such particles to harmfully act on theinner periphery of the sleeve portion 10g. Thus in the case of a pair ofgenerally horizontal nips N-l and N4 or even a pair of nips where thenip N-l is above the nip N-2, the essential requirement would be thatthe particle size and shape would be preferably generally spherical andof such size that it would not pass through the second nip N-Z orpartially clog the same in such a way as to cause marking, grooving orother harmful eflect on the interior or the overall body of the tubeportion 10g that passes through and is collapsed at the second nip N2.

In the ideal situation the bed 20 is maintained in particulate generallyphysically fluid state at a relatively lower level just above the nipN-l, in a state of continuous circulation such that it does not evenapproach the second nip N-2 and any of these various undesirablepossibilities are thereby avoided. As here shown, the level L of thefluid bed 20 is actually below the midpoint between the nips N- l and N2and substantially no chance of any individual particles being carriedupwardly to the second nip N2 is afforded. On the other hand, theparticles as individuals in the bed 20 are intended to carry out thefunction of removal of the traces of liquid which had previouslycollected on the surface of the inner periphery of the tube as it passedthrough the submerged nip in the phase change bath, where the submergednip actually maintains a column of phase change liquid in the interiorof the tube as well as at the exterior thereof (during its change frommolten to solid form). Such liquid is, for most practical purposes;water but at least it is a liquid that is substantially insoluble in thebody of the solid plastic tube 10 and the solid plastic tube 10 is,likewise, substantially insoluble in such liquid in at least the tracequantities that appear in the region 10g as well as in the previouslymentioned phase change bath (not shown). On the other hand, a nominalamount of adherence between at least some of the particles in the bed 20and the inner periphery of the tube portion 10g is not undesirable.

This nominal amount of adherence can be achieved by virtue of the factthat the traces of liquid on the inner periphery of the tube in theregion 10g may be, for example, water and the particles may be solidswhich tend to pick up water by capillary action or similar phenomena,but which have sufliciently low weight that they have a tendency to bemore or less continously moved upwardly along the inner periphery of theopened tube portion 10g. This sort of movement of the particles upwardlyalong the inner periphery of the opened tube portion 16g amounts to amovement of the particles upwardly along the outer peripheral portion ofthe fluid bed of particles 20 and a type of recirculation within the bed20 such that those particles in the middle of the bed 20 will tend todrop down and replace thosebeing carried generally upward along theinner periphery of the tube 10g. In this way, fresh particles areconstantly brought into contact with the inner periphery of the expandedtube 10g and this is advantageous.

The manner in which the particles in the bed effect removal of water orsimilar traces of liquid on the inner periphery of the expanded tube 10gis important at least to the extent that such particles do not losetheir solid phase condition. Thus a collection of calcium chlorideparticles might not be desirable for any prolonged operation becausesuch particles tend to collect so much water that they ultimately areconverted to a concentrated liquid solution. On the other hand, whilethe calcium chloride particles were in solid condition they might bevery effective in removing traces of moisture because of their extremelygreat attraction to such traces of moisture.

Preferred type of particles for this purpose are waterlacking orrelatively dry fibers, water-lacking or com paratively dry nylonparticles (sometimes referred to in the art as fused or dehydratednylon), or many other similar particles which are relatively lightweightin character but which are generally not capable of being caused toadhere to the inner periphery of the moving plastic sleeve 10g simply byvirtue of the traces of moisture or other liquid thereon to the extentthat they would be carried all the way to the second nip N-2. Acommercially available product usable in this procedure is referred toas sintered nylon. As previously mentioned, a much less expensivematerial also usable in the instant method and apparatus would be driedor water-lacking cellulose in any of its various forms including typicalpaper pulp fibers which have been dried. Most of these solids which havejust been described as particulate materials are not necessarily roundbut they do pick up the liquid (water) traces by a type of capillaryaction so that they do not lose their solid state condition during theirfunction.

It will also be appreciated that the fine particulate material used ischemically and physically essentially inert with respect to the solidplastic tube 10g, with and without any water or other liquid that it maypick up. In general, it has already been indicated that it is usuallypreferably that it absorbs or picks up water by capillary action or someother type of phenomenon that does not alter its physical state in thesolid form. Its weight may be altered, of course, and this is ordinarilynot helpful. In fact, if the material is too light the overall bed maybe advantageously supplemented by the addition of metal shot or someother matreial that would serve to give added weight to the bed and thusassist in defining the desired configuration of the opened plastic tube10g. In general, any type of solid particulate material that is so lightor is so arranged that it would tend to ride along with the innerperiphery of the plastic tube 10g clear to the second nip N-2 would notbe desirable because the tendency to clog this nip should be avoidedand, therefore, it is preferable to maintain the solid fluid bed at alevel spaced from the second nip N-2. Most conveniently, this is donesimply by positioning the second nip N-2 substantially above the level Lof the bed 20 and using solid particulate material of weight at leastsignificantly greater than that merely of the air or other gasthereabove so that it will 'not tend to ride all the way up to the nipN2, even though it will tend to be more or less continuously moved atits outer periphery to afford the desired circulation within the fluidbody of the bed 20 itself. The bed 20 is made up of solid particles butit is referred to as fluid in character, much in the manner in which theskilled workers in the art refer to what is known as fluid bed drying,when gases are passed through moist solid particles to vaporize andremove the moisture while fluidizing the bed of particles. There is noreal confusion in thus referring to what has already been described assolid particles as being part of a fluid bed 20, at least insofar as theskilled worker in the art is concerned. In respect to the fluidized orfluidizable character of the bed 20, however, it will be appreciatedthat there is a certain amount of desirability in haying this bed formedof particles which have at least a limited amount of adherence to theinner periphery of the expanded plastic tube 10g while they are carryingout their essential function of collecting the traces of liquid thereonso that the recirculation at the periphery of the particle bed 20 willbe carried out for the most advantageous operation of the instantinvention. It will be appreciated that this type of recirculation withinthe fluid bed 20 and/ or a type of recirculation at the peripherythereof is not absolutely essential if the solid particles will pass theliquid traces which they pick up from the inner periphery of the tube10g among each other and thus effectively present fresh liquid-starvedor water-starved solid bodies to the inner periphery continuously withinthe bed 20 so that the essential function thereof is carried out. And,again, in this respect it should be mentioned that all of theparticulate bodies in such bed 20 need not have the same or identicalcharacteristics. For example, some metal shot particles may be includedtherein and these particles will probably not be able to pick up verymuch water at any given moment (although they would not be expected tobe totally incapable of picking up water), whereas they would preferablybe mixed with highly liquid-starved or water-starved particles such asthe previously mentioned sintered nylon and/ or water-starved cellulosefibers or similar types of particles. Preferably, however, the particlesthemselves do have the function in the bed 20 of a fluid bed in thatthey tend to recirculate by moving upwardly about the periphery of thebed 20 so that fresh particles will be continuously contacting the freshareas of inner tube periphery brought into contact with the underside ofthe bed 29 leaving the nip N-1. Also, preferably these particles have aweight greater than not only that of the air or ambient atmosphere abovethe level L within the expanded tube 10g but also they have a weightwhich is sufficient to function in combination with any relaxation inthe tension of the plastic tube between the nips N-1 and N-Z such thatthey are easily capable of overcoming any ambient outside fluidpressures which might tend to or attempt to collapse the tube 10gbetween these nips N-l and N-Z. Actually, the positioning of the nipsN-l and N-2 may readily be such that expansion in the region 19g takeslace inherently merely by virtue of the relaxation of the tension andthe particles in the particle bed 20 would thus have little or nofunctional weight, but even then they could not be of such character asto create a vacuum or a negative pressure diiferential'between theoutside and inside of the tube portion 10g, which is ordinarilyimpossible in the case of any solid material. Going to the otherextreme, the particles in the bed20 should not have such a great weightthat they would actually generate forces against the inner periphery ofthe expanded plastic tube 10g that would exceed the modulus ofelasticity or that would cause rupture thereof.

In the ordinary operation of the instant device, the fluid bed 20 willoperate for a subtantial period of time continuously recirculating andcontinuously removing the relatively minute traces of liquid carried bythe inner periphery of the plastic tube in the region 10g, butultimately these particles may reach a stage where they have acquiredtoo much moisture and/ or too much liquid from the inner periphery ofthe plastic tube10 and then it becomes desirable to replace the samewith newer fresh liquid-starved or water-starved particles. This couldtake place every twenty-four hours, every week or even every monthdepending upon the amount of liquid actually carried by the plastic tube12 on its inner periphery into the bed 20. On the other hand thereplacement of the bed 20 with fresh material does not constitute achange or consumption of the actual fluid bed itself but merely analteration thereof and the fluid bed 20 is a functioning part of theoverall drying apparatus. The material consumed is the'liquid on theinner periphery of the plmtic sleeve 10. The replacement of particlespartially or completely in the fluid bed 20 can take place quite readilysimply by severing the plastic tube in the region 10g above the level Land permitting the top portion of the plastic tube to pass on into thesubsequent conversion system while the festoon system 11 takes up theslack temporarily without any real reduction in speed of movement of thecollapsed plastic tube 10. At this stage it will be appreciated that thesolid fluidized bed of particles 20 can ordinarily not be completelyremoved or cleaned from the position here shown and can only bepartially replaced by fresh particles, but this can be done very rapidlyand in the course of normal operation and then the rising portion of thetube in the region 10g can readily be fed upwardly (or in any otherdirection which might be required) past the guiding boards 16 and 17 andinto the second nip N-Z so that the overall drying operation maycontinue for whatever the usual period of time may be between theoperational changes during which the particulate bed 20 is partiallyreplaced by fresh liquid-starved particles. Those skilled in the arewill readily recognize that this phase of the operation is notparticularly complicated and it may be that some of the plastic tubewould have to be fed off in a different direction for a brief momentwhile this change is taking place in the particulate bed 20 but therewould be only a very nominal amount of plastic tube so expended and thechanges in the fluid bed 20 could be caused to take take place veryrapidly. Also, it will be appreciated by those skilled in the art thatduring conversion it is necessary often to cause breaks in the plastictube in order to change from one converter system to another, so therecan easily be arranged a timing in this situation such that there is nowaste whatsoever of plastic tube. All of such operations are well withinthe skill of the art, once the instant disclosure has been explained tothe skilled worker and need not be described in further detail herein.

To reiterate to some extent, it will be appreciated that one of theaspects of the instant invention involves a method of removing traces ofliquid carried on the interior periphery of a substantially flattenedtubular solid thin flexible elastic sheet material in which such liquidis substantially insoluble, which comprises driving said flattened sheetmaterial longitudinally of its tubular axis by longitudinally spacedopposed pairs of co-moving surfaces engaging and completely flatteningsuch tubular material along longitudinally spaced generally transverselyaligned generally upper and lower narrow regions of engagement, drivingsuch tubular material via driving engagement at such longitudinallyspaced regions at relative driving speeds producing longitudinal tensionin said sheet therebetween that is substantially beneath the modulus ofelasticity of and rupturing force on the sheet, and maintaining a bed ofsolid fine particulate material spaced beneath the aforesaid upperregion and entrapped against downward longitudinal movement within thetubular sheet by said lower region, said bed of particles engaging theinterior of the longitudinally moving tubular sheet and applyingdownward and transversely outward forces to the interior of the sheetfor the longitudinal height of such bed to subject the sheet to greatertension than that applied by said longitudinally spaced drivingengagement but still substantially below said sheet modulus ofelasticity and rupturing forces to bulge said tube outwardly immediatelyabove said lower region by direct engagement between the sheet surfaceinner periphery and an outer peripheral layer of particles in the bedwhich layer of particles is continuously being moved upwardly andrecycled back into the upper portion of the bed while being replacedcontinuously by particles from the lower portion of the bed reforminglower outer peripheral layers of such bed for continuous particlerecycle and contact with the moving sheet inner periphery, saidparticles being non-tacky and substantially non-adherent to such innersheet peripheral surface but being highly receptive of such liquid withthe discrete individual bodies of such particles while retaining thegenerally particulate and mobile character of such fine particlesaffording the aforesaid continuous particle layer recycle and contact offresh particles with the inner periphery of said tube.

It will be understood that modifications and variations may be effectedwithout departing from the spirit and scope of the novel concepts of thepresent invention.

I claim as my invention:

1. A method of removing traces of liquid carried on the interiorperiphery of a substantially flattened tubular solid thin flexibleelastic sheet material in which such liquid is substantially insoluble,which comprises driving said flattened sheet material longitudinally ofits tubular axis by longitudinally spaced opposed pairs of comovingsurfaces engaging and completely flattening such tubular material alonglongitudinally spaced generally transversely aligned generally upper andlower narrow regions of engagement, driving such tubuar material viadriving engagement at such longitudinally spaced regions at relativedriving speeds producing longitudinal tension in said sheet therebetweenthat is substantially beneath the modulus of elasticity and rupturingforce on the sheet, and maintaining a bed of solid fine particulatematerial selected from the group consisting of sintered nyion,dehydrated cellulose, dehydrated nylon and mixtures thereof incombination with a predetermined portion of metal shot spaced beneaththe aforesaid upper region and entrapped against downward longitudinalmovement within the tubular sheet by said lower region, said bed ofparticles engaging the interior of the longitudinally moving tubularsheet and applying downward and transversely outward forces to theinterior of the sheet for the longitudinal height of such bed to subjectthe sheet to greater tension than that applied by said longitudinallyspaced driving engagement but still substantially below said sheetmodulus of elasticity and rupturing forces to bulge said tube outwardlyimmediately above said lower region by direct engagement between thesheet surface inner periphery and an outer peripheral layer of particlesin the bed, which layer of particles is continuously being movedupwardly and recycled back into the upper portion of the bed while beingreplaced continuously by particles from the lower portion of the bedreforming lower outer peripheral layers of such bed for continuousparticle recycle and contact with the moving sheet inner periphery.

References Cited UNITED STATES PATENTS 2,476,140 7/1949 Francis 264-3,214,327 10/1965 Wicker et al 34-95 X 3,275,549 9/1966 Crabb et al 349X 3,275,723 9/1966 Cappuccio 264-210 X FREDERICK L. MATTESON, JR.,Primary Examiner. D. A. TAMBURRO, J. J. CAMBY, Assistant Examiners.

1. A METHOD OF REMOVING TRACES OF LIQUID CARRIED ON THE INTERIOR PERIPHERY OF A SUBSTANTIALLY FLATTENED TUBULAR SOLID THIN FLEXIBLE ELASTIC SHEET MATERIAL IN WHICH SUCH LIQUID IS SUBSTANTIALLY INSOLUBLE, WHICH COMPRISES DRIVING SAID FLATTENED SHEET MATERIAL LONGITUDINALLY OF ITS TUBULAR AXIS BY LONGITUDINALLY SPACED OPPOSED PAIRS OF COMOVING SURFACES ENGAGING AND COMPLETELY FLATTENING SUCH TUBULAR MATERIAL ALONG LONGITUDINALLY SPACED GENERALLY TRANSVERSELY ALIGNED GENERALLY UPPER AND LOWER NARROW REGIONS OF ENAGEMENT, DRIVING SUCH TUBULAR MATERIAL VIA DRIVING ENGAGEMENT AT SUCH LONGITUDINALLY SPACED REGIONS AT RELATIVE DRIVING SPEEDS PRODUCING LONGITUDINAL TENSION IN SAID SHEET THEREBETWEEN THAT IS SUBSTANTIALLY BENEATH THE MODULUS OF ELASTICITY AND RUPTURING FORCE ON THE SHEET, AND MAINTAINING A BED OF SOLID FINE PARTICULATE MATERIAL SELECTED FROM THE GROUP CONSISTING OF SINTERED NULON, DEHYDRATED CELLULOSE, DEHYDRATED NYLON AND MIXTURES THEREOF IN COMBINATION WITH A PREDETERMINED PORTION METAL SHOT SPACED BENEATH THE AFORESAID UPPER REGION AND ENTRAPPED AGAINST DOWNWARD LONGITUDINAL 